a framework for behavior consistent specialization of artifact-centric business processes

Sira Yongchareon1, Chengfei Liu1, and Xiaohui Zhao2

1Faculty of Information & Communication TechnologiesSwinburne University of Technology, Australia

2Faculty of Information Sciences and EngineeringUniversity of Canberra, Australia

A Framework for Behavior-Consistent Specialization of Artifact-Centric Business Processes

BPM’12, 3-6 September 2012, Tallinn, Estonia

BPM’12, 3-6 September 2012, Tallinn, Estonia Sira Yongchareon, Chengfei Liu, and Xiaohui Zhao 2

Introduction Artifact-centric process modeling Motivation and issues in specialization

A framework for specializing artifact-centric processes Specialization methods Behavioural consistency

Conclusion

Outline


Introduction : ACP Modeling Artifact-Centric Process (ACP) modeling approach

Focuses on business artifact (entities), e.g., Purchase Order, Invoice

How they evolve from creation to completion (or archived) throughout a process

Purchase Order (PO)

deliveringclosed

confirmed

Shipping Order (SO)

In transitarrived

Invoice (IV)

unpaidcleared

billing

approving

canceled

filledsupplying

issued

Synchronization


Introduction : ACP Modeling A simple ACP Model

Consists of (1) Artifact classes (with attributes and states), (2) Tasks, and (3) Business rules (ECA with post-condition)

Purchase Order (PO)

deliveringclosed

confirmed

Shipping Order (SO)

In transitarrived

Invoice (IV)

unpaidcleared

billing

approving

canceled

filledsupplying

issued

Synchronization (by sync rule)


Introduction : Motivation to specialization

Facilitate natural reuse Likewise in an object-oriented design approach artifact-centric

approach lends itself to componentization in a natural way

Enable different levels of comparison and reporting across specializations (at both artifact and process levels)

How many (both Online and Offline) invoice not yet cleared ? From those, how many order already arrived to customers? A

supplier urgently needs to collect those debts

Generic Purchasing Process Model

PurchaseOrder

Shipping Order

Invoice

Offline Purchasing Process Model

Offline PO

Shipping Order

Offline Invoice

specializesOnline Purchasing

Process Model

Web PO Shipping Order

Online Invoice

specializes

Quote


Introduction : Motivating Example Specializing a purchasing process (in supply chain domain)

Purchase Order (PO)

deliveringclosed

confirmed

Shipping Order (SO)

In transitarrived

Invoice (IV)

unpaidcleared

billing

approving

canceled

filledsupplying

issued

Buyer (L1) Supplier (L2) Logistics (L3)Purchase Order (PO)

Picking List (PL)

ready to fillFilled order

checking

Quote (Q)

created approving

approved

In stock

Shipping Order (SO)

In transit

arrived

Invoice (IV)

cleared

Shipping List (SL)

Queued

pickedcompleted

created confirmed

closed billing

canceled

filledaccepted

acquiring

delivering

ready to ship

created

Out of stock

issuedsent

Payment (P)

createdapproving

sent

Delivery Note (DN)

prepared

transferring

scheduled

dispatched

waiting

rejected

on hold

clearing

Specialized process

Generic process

How can be constructed from such that is observable from ?


Introduction : Issues How to define specialization

Existing OO specialization approaches insufficient No definition for a process that consists of several objects Therefore, a process still treated as a single object

Dependencies between objects need to be considered

How to preserve behavioral consistency That allows aggregate monitoring/reporting (of instances of

different subtypes that belong to the same supertype) Requires observation consistency [Schrefel and Stumptner, 2002]

(or projection inheritance in [van der Aalst and Basten, 2002])

Note that specialization is done at the artifact level while the consistency is preserved at the process level


Framework : Overview Behavior-Consistent ACP Specialization

ACP Model , where is a set of artifact classes, is a set of tasks, is a set of business rules

Behavioral Model for ACP model and its artifacts Specialization methods (on artifacts and their dependencies) Observation consistency rules

Specialized business process model Õ’

Base business process model Õ specializes

Behavior of Õ Behavior of Õ’consistent with

Behavior-consistent process specialization


Framework : Overview Specialization methods

Artifact refinement Refine an existing artifact in a specialized process An existing business rule refined into a set of specialized rules (may

include sync rules)

Artifact extension Add a new artifact in a specialized process New business rules added (includes sync rules between existing

artifact(s) and the added artifact)

Artifact reduction (not in the paper)

Delete an existing artifact Existing business rules deleted/modified (abstracted)


Framework : The Big Picture


Framework : Behavior Models Artifact lifecycle ()

, artifact lifecycle (model) of artifact can be derived from , where

is a set of states, is the initial state is transition relations

ACP lifecycle () = synchronized product by composing all artifact lifecycles in

Given two sound artifact lifecycles, the composition between them needs not to be sound

Their synchronization may cause a deadlock

Lifecycle composition


Framework : ACP Specialization ACP specialization mapping function ()

specializes based on where is an empty (null) element

and specialization methods Artifact refinement and artifact extension (and reduction) are

expressed by For each method, mapping condition needs to be satisfied

(detailed in the paper) Note that extension uses


Framework : ACP Specialization Consider from behavioral aspect artifact lifecycles

and their synchronizations

Given and , we have Artifact lifecycle specialization mapping ()

and

Synchronization specialization mapping () , where is a set of specialized sync rules between


Framework : B-Consistency B-consistent specialization relation

Based on weak bi-simulation (allows silent steps) Lifecycle is a B-consistent specialization of lifecycle iff = and and are weakly

bi-similar

is B-consistent is not B-consistent (state a may reach state c without passing state b) is B-consistent (replacing a transition related to state b with )

B-consistency of artifact does not transfer to B-consistency of process


Framework : Lifecycle fragment L-fragments used for capturing lifecycle specialization

L-fragment of lifecycle is defined as where,

is a set of states is transition relations within is a set of entry transitions and is a set of exit transitions of

Example

has a single entry and single exit transition and have multiple entries and multiple exits transitions


Framework : Atomicity property Atomic L-fragments (AL-fragments)

For individual L-fragment Based on SESE fragment (multiple entry/exit transitions allowed)

AL-fragments preserve B-consistency for refining a transition that has no sync

For synchronized L-fragments (between artifacts) Need to consider all related fragments it synchronizes with Based on sync rules used between synchronized fragments


Framework : Synchronization Region Synchronization region (S-region)

Represents a set of L-fragments that are synchronized, denoted ), where

is a set of L-fragments is a set of business rules used to sync L-fragments in

Example, = ({, },{, }) = ({, , },{, …, }), notice is not in


Framework : Synchronization Region Similar to atomicity for individual L-fragment (AL-

fragment), we define atomicity of synchronized L-fragments

Atomic S-region (AS-region) S-region is atomic iff

the composition of all (synchronized) L-fragments in is atomic, i.e., the synchronized product for is an AL-fragment

contains all sync rules used


Framework : Synchronization Region Example

is not an AS-region

is an AS-region

𝒍𝟑⨂ 𝒍𝟒

𝒍𝟑⨂ 𝒍𝟒

AL-fragment

NAL-fragment


Framework : Synchronization Region AS-region and B-consistency

Composition of all L-fragments in AS-region yields a (composite) AL-fragment in a specialized process

….and AL-fragment preserves B-consistency Therefore, AS-region preserves B-consistency (between

processes)

AS-region as a condition when applying specialization methods to guarantee the B-consistency between a specialized process and its base process


Framework : B-consistent Specialization B-consistent artifact refinement (with sync)

Refining a transition that sync with other artifact(s) by replacing the transition with synchronized L-fragment

Refined synchronized L-fragments must be able to form an AS-region


Framework : B-consistent Specialization B-consistent artifact extension

Adding a new artifact and synchronizing it with existing artifact(s) on refined L-fragment(s)

Added artifact must be able to form an AS-region with existing artifact(s)


Framework : B-consistent Specialization More complicated examples

Artifact refinement with nested refined fragment(s)

Multiple artifact extensions & refinements

C1

s1

C3C2

C4

s2

s1

s3

s2

s4s1 s2 s3

l4

s3 s5

s4

s6

l1

s2

s3

s1

l2l3l5


Framework: Example revisitPurchase Order (PO)

deliveringclosed

confirmed

Shipping Order (SO)

In transitarrived

Invoice (IV)

unpaidcleared

billing

approving

canceled

filledsupplying

issued

Buyer (L1) Supplier (L2) Logistics (L3)Purchase Order (PO)

Picking List (PL)

ready to fillFilled order

checking

Quote (Q)

created approving

approved

In stock

Shipping Order (SO)

In transit

arrived

Invoice (IV)

cleared

Shipping List (SL)

Queued

pickedcompleted

created confirmed

closed billing

canceled

filledaccepted

acquiring

delivering

ready to ship

created

Out of stock

issuedsent

Payment (P)

createdapproving

sent

Delivery Note (DN)

prepared

transferring

scheduled

dispatched

waiting

rejected

on hold

clearing

Specialized process

Generic process


Framework : Ongoing work Given any L-fragment of an artifact in the process, find

the minimal AS-region that includes such fragment Help to decide whether a refinement/extension in the

specialized process is valid Help to find all possible synchronized L-fragments that will be

affected by the reduction (abstraction) of artifact


Conclusion Behavior-Consistent Specialization framework

Facilitate natural reuse of BPs with the support of reporting/monitoring at both artifact and process levels

Observation consistency B-consistency notion – based on weak bi-simulation AS-region notion for synchronized fragments

B-consistent Specialization methods Artifact refinement Artifact extension Artifact reduction (opposite to extension)

Future work Consider nested (composite) states with parallelism (within an artifact) Extend analysis for a finer bi-simulation (e.g., branching, rooted bi-

simulation observation congruence)


Thank you

a framework for behavior consistent specialization of artifact-centric business processes

Technology

new artifact

process levels

purchasing process

artifact classes

artifact level

process levelbpm12

business artifact entities

estoniasira yongchareon